The hook portion of your Velcro strip is full of fuzz and it doesn’t stick anymore. Cleaning it is using typical methods and products is tedious, time consuming and not very effective.
The solution is a brush that is designed for use in extracting the embedded hair, threads, fabric and fuzz out of the hook portion of a Velcro fastener. The tines of the brush, spaced so that they travel between the rows of hooks, will be made of durable plastic that will be strong enough to pull the fuzz out of the Velcro while at the same time pliable enough so that it does not cut or break the hooks. The tines of the brush will also be retractable. When the brush is not being used the tines will be retracted but when the brush is applied to a Velcro surface, just prior to any brushing action, the tines will be pushed into the hook fabric to extract the fuzz. By design, the tines will embed themselves only as deep as the hook fabric which prevents them from breaking the hooks at the base. When done the tines will retract exposing any collected fuzz on the head of the brush for easy removal.
See the YouTube video: Velcro Cleaning Brush